In the Second (02) year complete 28 x 27 dichotomous ossification sequence matrices will be compared (a) between sexes, (b) between populations and (c) for the amount of sex differences between populations for Whites, American Negroes ("Blacks"), Mexican Americans, and Puerto Ricans--for North American populations--and including 3-5 specific Central American national groups as well as increasing the collection of stockpiled radiographs of chromosomal, genetic, and biochemical abnormalities and named syndromes to 600 or more on the basis of continuing cooperative research with institutions in Maryland, Ohio, Michigan, Switzerland, and Nigeria.